This invention relates generally to article coding machines for imprinting information upon articles traveling along the upper reach of a conveyor and more particularly is concerned with the provision of a coding machine for beverage containers such as cans and/or bottles which is capable of operating at a speed substantially greater than heretofore achieved yet with the maintenance of quality and the minimization of possible damage to either the containers and/or the immediate environment of the machine.
Coding or printing apparatus of the general type with which the invention is concerned applies an imprint at a predetermined location upon an article traveling along the reach of a conveyor as the article passes a printing location or station. Such apparatus is incorporated in article coding machines for applying such imprints to the underside of beverage cans and the caps of beverage bottles. However, to date, the speed of operation capable of being achieved by known coding machines is far less than the ability of the can and/or bottle feeding apparatus to deliver such containers to the coding machine. Increased speed of operation without resultant damage to the container and/or the environment of the machine has been a long-felt need of the packaging industry.
In addition to the desirability of high-speed operation, it is essential that the imprints applied to the containers be clear and properly located. As well, it is desirable that the mechanisms utilized be capable of easily being inspected, maintained and otherwise serviced without a substantial down time of the coding machine. Many coding machines incorporate imprinting apparatus of the rotary type which is characterized by the provision of a train of rotary members arranged so that their circumferential surfaces engage momentarily so that ink applied to one surface can be transferred and reapplied to the type face of a rotary printing head which in turn is placed in intercepting relationship with the surface of the article to be imprinted. In addition to the difficulties encountered with known coding machines in the interchange of type faces, cleaning and other routine maintenance operations, high-speed operation has resulted in the scattering of ink particles from the respective circumferential surfaces with increased occurrence as the speed of operation is increased. This is particularly encountered where liquid ink is utilized. The use of liquid ink is desired since it is effectively used upon wet surfaces commonly encountered where the articles are metal containers filled with a cool fluid so that condensation occurs, or containers having release coatings thereupon resulting from their process of manufacture. Powdered ink used in some high speed marking processes has a materially reduced effectiveness upon said containers. Substantial difficulties have been encountered in achieving proper registration or synchronization at the imprinting station, in passing the containers to and from the printing station and, as well, adjusting the printing heads so that the imprinted indicia will not be blurred or otherwise unsatisfactory such as partially printed, faint or improperly synchornized so as to be improperly distributed on the imprinted surface.
Although the term "high speed" is a relative term and of course differs depending upon the specific articles to be imprinted. High speed in the beverage can operations involves as many as 2,000 articles per minute and as many as 750 articles per minute where bottle beverage containers are considered. Operation at such "high speed" has been considered impossible, particularly where rotary-type imprinting apparatus is utilized. Coding machines which operate to apply indicia by way of electrostatic processes and do not require actual contact with the article surface are available, and do operate at relatively high speeds. However, the appearance of the imprint and the amount of information capable of being imprinted is considerably minimized and of minimum quality, particularly when utilized for coding wet or release coated surfaces. In addition, the cost of such equipment as well as the cost of operation of such equipment is considerably greater than machines which utilize the rotary type imprinting apparatus.
There are occasions when a certain group of articles traveling along the conveyor are not to be imprinted although such group travels in a line containing groups of articles which are to be coded. It would be desirable to render the imprinting means inoperative upon only the certain group and yet return the imprinting means to its operative condition for imprinting of the groups of articles whose coding is desired. This can be accomplished if the imprinting means can be displaced from its imprinting condition and then returned to its imprinting condition with retention of registration.
Accordingly, it is the intention of the invention to provide a high speed article coding machine which is capable of operation at an adjustable speed up to its maximum by virtue of improved synchronizing, positioning, and inking and imprinting apparatus.